from __future__ import annotations

import hashlib
import time


class EchoCache:
    def __init__(self, ttl_ms: int = 10_000):
        self._cache: dict[str, float] = {}
        self._ttl = ttl_ms

    def remember(self, chat_guid: str, text: str) -> None:
        key = self._build_key(chat_guid, text)
        self._cache[key] = time.monotonic()

    def is_echo(self, chat_guid: str, text: str) -> bool:
        key = self._build_key(chat_guid, text)
        ts = self._cache.get(key)
        if ts and (time.monotonic() - ts) * 1000 < self._ttl:
            return True
        return False

    def cleanup(self) -> None:
        now = time.monotonic()
        expired = [
            k for k, ts in self._cache.items()
            if (now - ts) * 1000 >= self._ttl
        ]
        for k in expired:
            del self._cache[k]

    def clear(self) -> None:
        self._cache.clear()

    @staticmethod
    def _build_key(chat_guid: str, text: str) -> str:
        raw = f"{chat_guid}:{text}"
        return hashlib.sha256(raw.encode()).hexdigest()[:16]